Circular clamp for balloons or the like

ABSTRACT

The apex end of a tape-reinforced balloon envelope is clamped between two segmented clamping rings which are mounted on a discshaped base member. The joint between the two segmented clamping rings is sealed by means of two resilient O-rings which function both as a gas seal and as a mechanical clamp for the reinforcing tapes and the balloon envelope. The O-rings rest in parallel grooves cut in the lower segmented ring and are compressed by matching tangs that project from the upper segmented ring. The grooves, tangs, and O-rings are dimensioned to provide the same O-ring compression factor for different thicknesses of material between the two segmented rings. The joints between the ends of the individual segments of the two clamping rings are staggered with respect to each other and each joint is sealed with a sealant or gasket material to block the escape of gas therethrough. A resilient gasket is interposed between the lower segmented clamping ring and the disc-shaped base member to which it is attached.

United States Patent Nelson CIRCULAR CLAMP FOR BALLOONS OR THE LIKELeroy E. Nelson, Minneapolis, Minn.

Assignee: Winzen Research, Inc., Minneapolis,

Minn.

Filed: Oct. 29, 1970 Appl. No.: 85,208

Inventor:

US. Cl ..24/243 K, 244/31 Int. Cl ..A44b 21/00, B64b 1/40 Field ofSearch.244/l26, 125 US, 31; 24/243 K,

References Cited UNITED STATES PATENTS Primary ExaminerDonald A. GriffinAttorney-Carlsen, Carlsen & Sturm [5 7] ABSTRACT The apex end of atape-reinforced balloon envelope is clamped between two segmentedclamping rings which are mounted on a disc-shaped base member. The jointbetween the two segmented clamping rings is sealed by means of tworesilient O-rings which function both as a gas seal and as a mechanicalclamp for the reinforcing tapes and the balloon envelope. The O-ringsrest in parallel grooves cut in the lower segmented ring and arecompressed by matching tangs that project from the upper segmented ring.The grooves, tangs, and O-rings are dimensioned to provide the sameO-ring compression factor for different thicknesses of material betweenthe two segmented rings. The joints between the ends of the individualsegments of the two clamping rings are staggered with respect to eachother and each joint is sealed with a sealant or gasket material toblock the escape of gas therethrough. A resilient gasket is interposedbetween the lower segmented clamping ring and the discshaped base memberto which it is attached.

14 Claims, 41 Drawing Figures PATENTEUausze I972 3 686, 721

sum 1 or z INVENTOR. ZEIPOY A/EZSd/V CIRCULAR CLAW FOR BALLOONS OR THELIKE BACKGROUND OF THE INVENTION This invention relates to circularclamps for sealing off the apex end of tape-reinforced balloons or thelike. In the manufacture of high altitude balloons for scientificresearch, it is customary to form the balloon envelope from a pluralityof relatively long, narrow gores which are made of a thin, tough,gas-impermeable plastic film such as polyethylene or the like. The goresare joined together at their side edges by heat seals or some other typeof gas impervious seam, and the seams are usually reinforced bysynthetic fiber tapes which constitute the load bearing elements of theballoon en velope. In such balloons, it is necessary to provide both amechanical clamp at the top or apex end of the balloon envelope formechanical joining the load bearing tapes together and a gas seal forthe envelope per se. Several different methods of achieving theseobjectives have been employed in the past, as disclosed, for example, inU.S. Pat. No. 2,919,082, which was issued to O. C. Winzen et al., onDec. 29, 1959, for a Balloon Having Reinforcing Structure," and in U.S.Pat. No. 2,771,256, which was issued to J. J. Ryan on Nov. 20, 195 6,for a Balloon With Load Supporting Tapes.

As disclosed in the above-noted patents, it has been the practice in thepast to provide two separate apex closures for the balloon envelope: amechanical clamp for the load bearing tapes, and a separate gas seal forthe envelope per se, as best shown in FIG. 2 of U.S. Pat. No. 2,771,256,and in FIGS. 7 and of U.S. Pat. No. 2,919,082. The use of separateclosures is, however, inconvenient in practice, and the principal objectof this invention is to provide a circular clamp that will function bothas a mechanical clamp and as a gas seal.

Several problems arise in connection with combining the mechanical clampand gas seal functions in a single circular clamp. Circular clamps havebeen used in the past for the mechanical clamping function alone, asdisclosed, for example, in FIG. 10 of U.S. Pat. No. 2,919,082, but suchcircular clamps have lacked the precision necessary to form a good gasseal. Moreover, because of the relatively large size required in suchclamps, the achievement of the necessary precision involves considerableexpense due to the fact that close tolerances are difficult to hold onlarge cast rings and mold costs are prohibitive because of size.Accordingly, it is a further object of this invention to provide a novelcircular clamp in which a relatively high degree of precision can beobtained at a relatively low cost.

SUMMARY OF THE INVENTION In accordance with this invention, theabove-noted objects are achieved by providing two segmented clampingrings which are mounted on a disc-shaped base member. The clamping ringsare made of a relatively large number of identical segments which can bemade by die casting, molding, or machining techniques. The segmentationof the clamping rings makes it possible to achieve a high degree ofprecision in the clamping rings at a relatively low cost. The individualsegments are butt-joined together, with the butt-joints between theupper and lower rings being staggered with respect to each other, andall of the butt-joints being rendered gas-impervious by means of asealant or gasket material. The joint between the two segmented clampingrings is sealed by means of two resilient 0- rings which function bothas a gas seal and as a mechanical clamp for the reinforcing tapes andthe balloon envelope. The two O-rings rest in parallel grooves cut inthe lower segmented ring and are compressed by matching tangs thatproject from the upper segmented ring. The grooves, tangs, and O-ringsare dimensioned to provide the same O-ring compression factor fordifferent thicknesses of material between the two segmented rings, withthe O-ring compression factor being great enough to withstand the normalmechanical shocks applied to the load bearing tapes which are to besecured between the two segmented clamping rings. A resilient gasket isinterposed between the lower segmented clamping ring and the disc-shapedbase member to which it is attached.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of a balloonwhich utilizes one illustrative embodiment of the invention.

FIG. 2 is a plan view taken upon the plane 22 of FIG. 1.

FIG. 3 is a cross-sectional view taken upon the plane 33 of FIG. 2.

FIG. 4 is a cross-sectional view taken upon the plane 4-4 of FIG. 4.

DESCRIPTION OF THE INVENTION FIG. I is an elevation view of a typicalballoon which utilizes one illustrative embodiment of the invention. Theballoon envelope comprises a plurality of relatively long,- narrow gores10 which are made of a thin, tough, gas-impervious plastic film such aspolyethylene or the like. The gores 10 are heat sealed at their sideedges to each other and the side edge seams are reinforced by loadbearing tapes 12 which are made of synthetic fiber, or some othersuitable load bearing material. Load bearing tapes 12 are preferablycovered with a plastic film and are heat sealed to their respectiveseams. The tapes 12 are clamped at the top or apex end of the balloonenvelope by a clamping ring assembly 14 and are secured at their lowerend to a load bearing ring 16 to which the pay load of the balloon (notshown in the drawings) is attached. The lower or appendix end of thegores 10 are terminated at 18 and left open in this example to form anopen appendix. It will be understood by those skilled in the art,however, that the gores 10 could be sealed together at their appendixend if desired, and also that in this case a second clamping assembly 14could be used at the appendix end of the balloon.

FIGS. 2, 3, and 4 show the structural details of the clamping ringassembly 14, which is mounted on a relatively flat, disc-shaped baseplate 20. Base plate 20 is made of sheet metal and has two handles 22and 24 attached thereto for handling purposes. The clamping ringscomprise a plurality of identical segments which are disposed in agenerally circular pattern around the periphery of base plate 20 and areattached thereto by bolts. As best shown in FIGS. 3 and 4, a circularresilient gasket 26 is interposed between the lower clamping ring andbase plate 20. The lower clamping ring comprises a plurality ofidentical segments 28 which are attached to base plate 20 by bolts 30which extend through openings in base plate 20 and gasket 26 and engagethreaded openings in the segments 28. The segments 28 are arc-shaped andhave radially oriented ends which form a relatively tight butt-jointwhen the segments are disposed in a circle around the periphery of baseplate 20 as shown in FIG. 2. In this particular embodiment of theinvention, the completed ring contains twelve of the segments 28, but itwill be apparent to those skilled in the art that the number of segmentsin the ring can be varied at will, and also that the length of thesegments must be computed in accordance with the number of segments sothat they will fit together when they are disposed in a circle aroundthe periphery of base plate 20 as shown in FIG. 2. The butt-jointsbetween the individual segments 28 are preferably sealed by means of asuitable adhesive/sealant or gasket material to block the escape of gastherethrough.

Each of the individual segments 28 have two arcshaped, coaxial groovesfor receiving two resilient rings 32 and 34, which act both asmechanical clamps and as gas seals for the balloon envelope andreinforcing tapes. The resilient O-rings 32 and 34 are compressed bytangs which project from the upper clamping ring, as will be describedin later paragraphs.

The upper clamping ring comprises a plurality of identical segments 36which are disposed in a generally circular pattern on top of the lowerclamping ring segments 28 but with the butt-joints between the uppersegments 36 being staggered with respect to the buttjoints between thelower segments 28 as shown in FIG. 2, where the solid radial linesaround the clamping ring indicate butt joints between the upper segments36 and the dashed radial lines indicate butt joints between the lowersegments 28. It will be understood by those skilled in the art that thisstaggering of the butt joints provides mechanical rigidity for theclamping rings and also improves the gas seal between the two rings. Theupper segments 36 are secured to lower segments 28 by means of studs 38(FIG. 3) and nuts 40. Studs 38 are screwed into threaded openings inlower segments 28 and project through matching openings in uppersegments 36 to engage the nuts 40. As shown in FIG. 2, six studs 38 areprovided for each of the upper segments 36, but it will be apparent tothose skilled in the art that a larger or smaller number of studs couldbe used if desired.

Each of the upper segments 36 has two arc-shaped, coaxial, downwardlyprojecting tangs 42 and 44 which are positioned to engage the center ofresilient O-rings 32 and 34 to apply a compressional force thereto. Thetangs 42 and 44 are narrower in width than the O-rings 32 and 34 andproduce the same compression in the 0- rings for different thicknessesof material between the upper and lower clamping segments. With respectto the design parameters for the O-rings 32 and 34 and the tangs 42 and44, it is preferable for the O-rings to fit snugly within their groovesand to be approximately flush with the top surface of lower segments 28in their uncompressed state. This condition is achieved by making thedepth and width of the grooves approximately equal to thecross-sectional diameter of the 0- rings. The tangs 42 and 44 must besufficiently narrower than the O-rings to prevent the material betweenthe two clamping rings from being cut or sheared between the edge of thetang and the matching edge of the groove when the upper and lowersegments are clamped together. in quantitive terms, this means that thedifference of width between the tangs and their on posing grooves shouldbe equal to or greater than approximately twice the maximum width of thematerial which is to be clamped between the two segments. In thedisclosed embodiment, the thickness of the material varies from 0.025inch to 0.075 inch, and the following dimensions have been found to besatisfactory in producing substantially equal compression of the 0-rings:

O-ring diameter 0.075 inch Groove depth=0.275 inch Groove width 0.280inch Tang width 0. l 87 inch Tang depth 0.050 inch The corners of thetangs and grooves are preferably rounded to avoid damage to the materialthereinbetween. It should be understood that the above-noted dimensionsare exemplary and that considerable variation may be necessary ordesirable in other applications of the invention.

In the disclosed embodiment of the invention, the apex end of theballoon envelope is doubled around the hoop 46 and heat sealed to itselfon the outside of the clamping ring assembly. Although this is desirablebecause it increases the strength of the mechanical clamping of theballoon envelope and the load bearing tapes, it should be understoodthat the hoop 46 is not a part of the invention, and that the hoop 46 isoptional in the sense that the clamping assembly 14 can be used withouthoop 46 if desired.

From the foregoing description it will be apparent that this inventionprovides a novel circular clamp which functions both as a mechanicalclamp and as a gas seal at the apex end of a tape-reinforced balloonenvelope, and also provides a relatively high degree of precision at arelatively low cost, and maintains an effective gas seal in spite ofvariations of thickness in the balloon envelope. And although thisinvention has been 7 described in connection with one illustrativeembodiment thereof, it should be understood that many modifications canbe made in the disclosed structure without departing from the basicprinciples of this invention. For example, although two O-rings havebeen used in the disclosed embodiment, it is clear that three or four ormore O-rings can be employed if necessary in other embodiments where atighter seal is required. Many similar modifications of the disclosedstructure will be apparent to those skilled in the art, and thisinvention includes all modifications falling within the scope of thefollowing claims.

I claim:

1. A circular clamp for sealing the periphery of an aperture in balloonsor the like comprising a discshaped base member, a first plurality ofclamp segments attached to one side of said base member and disposed ina generally circular pattern around the periphery thereof to form afirst segmented clamp ring, a like second plurality of clamp segments,means connecting said second plurality of clamp segments to said firstplurality of clamp segments to form a second segmented clamp ring, andat least one resilient O-ring and the envelope of a balloon or the likedisposed between said first and second segmented clamp rings.

2. A circular clamp as defined in claim 1 and further comprising agroove formed in said first plurality of clamp segments for receivingsaid resilient O-ring and a projecting tang formed in said secondplurality of clamp segments for applying a compressive force to saidresilient O-ring.

3. A circular clamp as defined in claim 2 wherein the depth and width ofsaid groove is approximately equal to the cross-sectional diameter ofsaid O-ring.

4. A circular clamp as defined in claim 3 wherein said projecting tangis narrower in width than said groove.

5. The apparatus of claim 2 in which the joints between the firstplurality of clamp segments and the joints between the second pluralityof clamp segments are staggered.

6. A circular clamp as defined in claim 1 and further comprising asecond resilient O-ring disposed between said first and second segmentedclamp rings.

7 A circular clamp as defined in claim 6 and further comprising twogrooves formed in said first plurality of clamp segments for receivingsaid first and second resilient O-rings and two projecting tangs formedin said second plurality of clamp segments for applying a compressiveforce to said first and second resilient O- 6 rings.

8. A circular clamp as defined in claim 7 wherein the depth and width ofeach groove is approximately equal to the cross-sectional diameter ofthe corresponding 0- ring.

9. A circular clamp as defined in claim 8 wherein said projecting tangsare narrower in width than the corresponding groove.

10. A circular clamp as defined in claim 9 and further comprising aresilient gasket disposed between said first segmented clamp ring andsaid base member.

11. A circular clamp as defined in claim 10 and further comprising anadhesive/sealant material disposed between the segments of said firstsegmented clamp ring.

12. The apparatus of claim 7 in which the joints between the firstplurality of clamp segments and'the second plurality of clamp segmentsare staggered.

13. The apparatus of claim 6 in which the joints between the firstplurality of clamp segments and the second plurality of clamp segmentsare staggered.

14. The apparatus of claim 1 in which the joints between the firstplurality of clamp segments and the joints between the second pluralityof clamp segments

1. A circular clamp for sealing the periphery of an aperture in balloonsor the like comprising a disc-shaped base member, a first plurality ofclamp segments attached to one side of said base member and disposed ina generally circular pattern around the periphery thereof to form afirst segmented clamp ring, a like second plurality of clamp segments,means connecting said second plurality of clamp segments to said firstplurality of clamp segments to form a second segmented clamp ring, andat least one resilient O-ring and the envelope of a balloon or the likedisposed between said first and second segmented clamp rings.
 2. Acircular clamp as defined in claim 1 and further comprising a grooveformed in said first plurality of clamp segments for receiving saidresilient O-ring and a projecting tang formed in said second pluralityof clamp segments for applying a compressive force to said resilientO-ring.
 3. A circular clamp as defined in claim 2 wherein the depth andwidth of said groove is approximately equal to the cross-sectionaldiameter of said O-ring.
 4. A circular clamp as defined in claim 3wherein said projecting tang is narrower in width than said groove. 5.The apparatus of claim 2 in which the joints between the first pluralityof clamp segments and the joints between the second plurality of clampsegments are staggered.
 6. A circular clamp as defined in claim 1 andfurther comprising a second resilient O-ring disposed between said firstand second segmented clamp rings.
 7. A circular clamp as defined inclaim 6 and further comprising two grooves formed in said firstplurality of clamp segments for receiving said first and secondresilient O-rings and two projecting tangs formed in said secondplurality of clamp segments for applying a compressive force to saidfirst and second resilient O-rings.
 8. A circular clamp as defined inclaim 7 wherein the depth and width of each groove is approximatelyequal to the cross-sectional diameter of the corresponding O-ring.
 9. Acircular clamp as defined in claim 8 wherein said projecting tangs arenarrower in width than the corresponding groove.
 10. A circular clamp asdefined in claim 9 and further comprising a resilient gasket disposedbetween said first segmented clamp ring and said base member.
 11. Acircular clamp as defined in claim 10 and further comprising anadhesive/sealant material disposed between the segments of said firstsegmented clamp ring.
 12. The apparatus of claim 7 in which the jointsbetween the first plurality of clamp segments and the second pluralityof clamp segments are staggered.
 13. The apparatus of claim 6 in whichthe joints between the first plurality of clamp segments and the secondplurality of clamp segments are staggered.
 14. The apparatus of claim 1in which the joints between the first plurality of clamp segments andthe joints between the second plurality of clamp segments are staggered.